ANATOMIC, ABERROMETRIC, AND BIOMECHANICAL CHARACTERISTICS IN PATIENTS WITH MARFAN SYNDROME

Manuel Alejandro Garza León MD

The author have no financial interest in the subject matter of this poster.

[email protected]

Instituto para Preservación de la Visión

Introduction

    Marfan syndrome (MFS) is an autosomal dominant disorder of connective tissues, with an incidence of 1:10,000. The systems affected are the skeletal, cardiovascular, and pulmonary systems, skin and ocular system.

According to the Gent classification, the ophthalmologic major criterion is ectopia lentis. There are also 3 minor ophthalmologic criteria    Abnormally flat cornea Increased axial length of the globe Hypoplastic iris or ciliary muscle dysfunction.

Purpose

 To report the anatomical, optical and biomechanical corneal characteristics in patients with Marfan Syndrome  Anatomical  Mean keratometry  Central pachimetry  Optical  Corneal aberrations represented by zernike polynomials  Biomechanical  Corneal hysteresis  Corneal resistance factor

Methods

    Prospective, transversal and observational study of patients with confirmed diagnosis of Marfan Syndrome without history of corneal trauma, infection, disease or surgery, Glaucoma or Diabetes The anatomical and aberrometrical characteristics was measured with Rotating Scheimpflug Camera (Pentacam, Oculus)   The readings were taken as described in the instructions guide in automatic release mode.

Only scans registering as ‘‘OK’’ on the instrument’s ‘‘Examination Quality Specification’’ were used for analysis.

The biomechanical characteristics was measured with the Ocular Response Analyzer (ORA, Reichert).

 The measures was made 4 times and represented by his average. All the studies was made by the same person.

Results

Demographic information

mean age was 24 ± 10.79 years (range, 11-39)

Results

Iris and lens characteristics

Iridodonesis 80% Phacodonesis 100% * Subluxation of lens 100% * Subluxation without pharmacological pupillary dilation 88.24%(15/17) Localization of the subluxation Superonasal Inferior Superotemporal 41.2% (7/17) 35.29% (6/17) 23.53% (4/17) * 3 eyes of 2 patients was aphakic because a spontaneous posterior lens dislocation

Results

Corneal characteristics

Anatomical

Mean Sim K 40.49±1.54 D (38.7 to 42.7 D) 80% of eyes has less than 42 D Flat Sim K 39.45±1.55 D (37.7-41.9 D) Step Sim K 41.52±1,62 D (39.2-43.7) Central corneal thickness 562±37.23 µm (506-626 µm)

Results

Corneal characteristics

Aberrometric

Trefoil 0.00085±0.00029 µm (0.00064-0.00106 µm) Coma 0.00197±0.00016 µm (0.00186-0.00209 µm) Tetrafoil 0.00068±0.0004 µm (0.00037-0.00098 µm) aberration coefficient * 1.55±0.37 (1.1-2.5) * Coefficient that the Oculus Pentacam system calculates from the Zernike analysis with normal values are less than 1

Biomechanical

Corneal Hysteresis 9.13±1.49 mmHg (7.1-12 mmHg) Corneal Resistence Factor 9.09±2.41 mmHg (4.8-13.6 mmHg)

Discussion

   Our number of aphakic eyes (15%) its more than the reported previously (2--3% of eyes) *  maybe because our patients became from an exclusive ophthalmic practice. Of the other 17 patients, all had phacodonesis and subluxation of the lens this results are similar to the 86% reported by Sultan y coworkers ¥ . 80% of patients with mean keratometry less than 42 D similar to the reported by Heur and associated (74.5%) * Nemet AY, Assia EI, Apple DJ, Barequet IS. Surv Ophthalmol. 2006;51:561-75 ¥ Sultan G, Baudouin C, Auzerie O, et al. Invest Ophthalmol Vis Sci.

2002;43:1757-64.

Heur M, Costin B, Crowe S,et al. Am J Ophthalmol. 2008;145:997-1001

Discussion

 Central corneal thickness 562±37.23 µm(range, 506 - 626 µm) similar to reported by Heur and collegues with US pachymetry (CCT of 543.5 ±37.3µm) but differs with Sultan y coworkers who reported a significant decrease in pachymetry in MFS patients (502 ± 41.9 µm) compared with the controlled group with Orbscan pachymetry  Racial differences in CCC could explain our difference other possible explications are the different equipments used.

Sultan G, Baudouin C, Auzerie O, et al. Invest Ophthalmol Vis Sci. 2002;43:1757-64.

Heur M, Costin B, Crowe S,et al. Am J Ophthalmol. 2008;145:997-1001

Discussion

 Optical corneal characteristics measured as aberration coefficients, All the patients had a patological aberration coefficient values 1.55±0.37 (range, 1.1 2.5) Normal Value less than 1.

  In vivo confocal microscopy findings reported by the team of Sultan and Iordaniou found an alteration of the extracellular matrix in the stroma with an abnormal Z-scan profiles with an increased stromal back scattering of light and a brightly hyperreflective lines of extracellular matrix could indicate the presence of abnormal fibrillin in abundance in the stroma or a different spectrum of reflectivity of the abnormal fibrillinin. All this changes may produce a histological irregularity manifested as corneal aberrations Sultan G, Baudouin C, Auzerie O, et al. Invest Ophthalmol Vis Sci. 2002;43:1757-64.

Iordanidou V, Sultan G, Boileau C, et al. Cornea. 2007;26:787-92

Conclusions

  The biomechanical properties of corneas of Marfan patients in our group are within normal values reported in the literature, the Corneal Hysteresis was 9.13±1.49 mmHg (range, 7.1-12) and the corneal resistance factor 9.09±2.41 mmHg (range, 4.8-13.6).

In conclusion  In our studied group, the corneas of Marfan Syndrome patients presents a flat corneas with a normal pachymetry and biomechanical properties but with a abnormal aberration coefficient values. del Buey MA, Cristóbal JA, Ascaso FJ, et al. Invest Ophthalmol Vis Sci. 2009;50:3199-202 Ortiz D, Piñero D, Shabayek MH, et al. J Cataract Refract Surg. 2007;33:1371-5